Pulse generator with output amplifier controlled by respective sequentially pulsed driver-amplifiers controlling leading and trailing edges



Jan. 26, 1965 M. L.. JONES ETAL 3,167,717

PULSE GENERATOR WITH OUTPUT AMPLIFIER CONTROLLED BY RESPECTIVE SEQUENTIALLY PULSED DRIVER-AMPLIFIERS CONTROLLING LEADING AND TRAILING EDGES Filed Deo. 17, 1962 United States Patent Office 3,167,717 Patented Jan. 26, 1965 PULSE GENERATOR WITH OUTPUT AMPLIFEER This invention relates to pulse generators and more particularly to pulse generators capable of producing square wave pulses with a iiat top and extremely fast rise and fall time leading and trailing edges approaching true square waves.

There is an ever increasing need to produce fast rise and fall time square wave pulses with at tops to lapproach the perfect square wave pulse in which the leading and trailing edges are parallel land in which Ithe at top lis normal to the edges. This perfect square wave pulsehas not been accomplished since electronic equipment inherently requires time in a sequence of operations to produce the wave. While many generators are known and commonly called square wave generators, these have only approached lthe generation of perfect square waves by developing the leading and trailing edges within a few microseconds to produce what appears to lbe a square wave but what is in fact a trapezoidal wave or, at best, an isosceles trapczoidal wave.

In the present invention a high output, good quality square wave is generated in a novel circuit combination to decrease the rise time to a range from six to twenty nanoseconds and the fall time to a range `from fifteen to thirty nanoseconds. In this invention the square wave pulse generator is triggered by positive and negative pulse signals in sequence which may -be produced Ifrom the differentiation of a generally applied square wave of adjustable width. The positive yandnegative pulse signals are applied through an input transformer with two oppositely poled secondaries to two driver circuits. One driver circuit will amplify only the positive input signal while the other driver circuit ampliies only the negative input pulse, both driverv circuits producing amplified positive.

pulses in the same time sequence as the input positive and negative pulse signals. Each driver includes an amplifier transformer coupled to a blocking oscillator to lproduce fast rise times for the two pulses. The output from the driver circuit producing the first pulse in sequence is coupled through a transformer to an output amplifier coupled as a blocking oscillator with a cathode follower output` The output amplier has a damping circuit coupled to the grid input to dampen out overshoots of the input pulse, and a discharging circuit is coupled between this grid and the output of the other driver circuit to discharge and render nonconductive the output amplifier upon the application of the negative input pulse signal to the input transformer. A holding circuit is coupled across the grid and cathode output of the output amplifier to hold the cathode output voltage atavoltage rise level until discharged Y by the discharge circuit. Upon discharge or cutoff of the output amplifier, a pulse amplifier coupled between the grid and cathode output operates to accelerate or speed up the discharge rate to complete the trailing edge to the output square wave in the minimum of time. It is therefore a general object of this invention to provide a square wave generator, triggered by trigger pulses coextensive in time with the duration of the output square wave, that develops exceedingly fast rise and fall time leading and trailing edges with a connecting flat top closely approaching a true square wave.

These and other objects and the attendant advantages, features, and uses may became more apparent to those skilled in the art as the description proceeds when considered along with the accompanying drawing in which:

FIGURE l is a circuit schematic of a preferred emi bodiment of the invention, and

,y FIGURE 2 is a set of time related waveforms occurring at various terminals of FIGURE 1.

Referring more particularly to FIGURE 1, with occasional reference to FIGURE 2 as appropriate, there is shown a circuit schematic diagram of the pulse generator in which an input to terminals 10 and 11 is to the primary winding of an input transformer 12 having two Secondaries 13 .and 14. The input signal applied to terminalsv 1t) and 11 is shown by the waveform A in FIGURE 2 and may consist of time related pairs of positive and negative pulses in sequence, such as signals that may be produced bythe differentiation of a square wave. Secondary winding 13 of transformer 12 has one lead coupled to the grid of a triode amplifier tube 15 and the other terminal coupled through a grid biasing resistor 16 to a negative voltage source applied at terminal 17. The junction of the secondary winding 13 and the grid biasing resistor 16 is coupled to a capacitor 18 having its opposite plate coupled -to some fixed potential such as ground. The

cathode yof the triode amplifier 15 is directly coupled to the fixed potential .and its anode is coupled to a positive anode voltage source at terminal 19- through a primary winding 20 of coupling transformer 21 and an anode load resistor 22 in series. Resistor 23 is coupled in parallel with the primary winding 20 of transformer 21. The common junction or resistor 23, winding 20, and resistor 22 is coupled to one plate of a capacitor 24, the

opposite plate of which is coupled to the fixed potential v such as ground. A capacitor 25 has its opposite plates coupled to the negative voltage source 17 and ground potential, and a capacitor 26 has its opposite plates coupled between the positive anode voltage source 19 and ground.

Coupling transformer 21 has a secondary winding 30 having one lead coupled to the control grid of a blocking oscillator triode tube 31 and its opposite lead coupled through a grid biasing resistor 32 to a negative voltage source terminal 33. The negative voltage source terminal 33 is coupled to one plate of a capacitor v34, the opposite plate of which is coupled to ground. The cathode of blocking oscillator triode 31 is coupled through a cathode resistor 35 to ground and also has Aone plate of a capacitor 36 coupled directly thereto and the opposite plate coupled to the junction of the secondary Winding 30 and the grid biasing resistor 32. The anode of the triode 31 is coupled through a winding 37, which is in inductive relation with the secondary winding 30, and

through an anode biasing resistor 38 to an anode voltage f The output of the blocking oscillator is taken directly from the cathode on the output conductor 42.

The above description of the amplifier and blocking oscillator combination provides a driver circuit which is exactly duplicated in the circuit from 4the secondary winding 14 with the exception that the secondary windings 13 and 1'4 are oppositely polarized. In view of the similarity of elements and coupling arrangements in the lower ampliiier and` blocking oscillator providing a driver circuit as described for the above circuit, the elements of the lower circuit will be identified by the same reference characters primed By this construction and arrangement the pulse input A, as shown by FIGURE 2, applied atrthe terminals and 11 of input transformer 12 will cause amplification of the positive pulse in the upper driver circuit and the amplification of the negative pulse in the lower driver circuit to produce a sequence of positive pulses, respectively, Vfrom the upper and lower driverV output amplifier tetrode tube 50, and the other lead 51 i coupled tothe anode of a damping diode52, to the cathode lof aholding diode 53, and to the anode of 'apulse amplifier triode tube'54`. Damping diodertube 52 has a grid ycoupled directlyto the anode which causes operationy as a diode, and in like manner, the holding diodey 53 has a grid coupled directly to the anode toI make this tube likewise operate as a diode. The anode of thel holding diode 53 is coupled through4 a Zener diode 55 to the cathode lof the output amplifier tetrode 50, this` cathode being coupled through cathode resistors 56 and, 57 in series to the fixed potential, such as ground. The control grid of the output amplifier tetrode 50 is biased through the Zener `diode 55, as will later become clear, and a resistor- 58. kThe Zener diode 55 likewise has a capacitor 59'coupled in parallel therewith. lThe cathode of output amplifier tetrode 50 and the screen grid thereof are coupled in parallel to` capacitors 60 and 61. The

parallel coupling of capacitors 60 and 61 are paralleled in series by a plurality o-f Zener diodes, herein shown by diodes 62, 63, 64,and 65 topestablish the proper screen grid potential of tetrode 5t). The anode of theV output operation-will be given in the description of` operation, infra.

The Vout-put terminal V75 of the pulse generator circuit may be coupled to any Vcircuit in ywhich'high quality square waves are to ybe used but, for the purpose of illustration herein, is shown tovbe to the grid of the,

traveling wave tube illustrated within dotted lines 97. It is tofbe understood, however, that there are many uses and applications 'for highfquality square Waves and,

accordingly, the output 75 can beconnected to any such circuit and it is to be understood that the traveling wave tuhe is purely for example herein and is not to limit the use of the invention in any way.-

Operation In the operation of the circuit shown-andy described above for FIGURE l'let it be assumed thatV paired pulses, such as shown by A in FIGURE V2, are Vapplied to the Vinput transformer 12. The transformer 1-2 ispolarized as shown by the dotsrover the primary ywindingV and the two secondary windings 13 and 14 which causes the lirst yinsequence or positive pulse A to4 be applied as a positive pulse to the grid of the amplifier triode 15 and the negative pulse from the secondary 14' tobe applied asV a negative pulse to the grid of the amplifier 15. By reason of the negative bias from the source 17 to the grids of the amplifiers 15 `and 15', ythe positive pulse on the grid Vofamplifier 15 `Vwill cause tube conduction Land amplification of this positivefpulse to produce an ampliiier 50 is coupled through a transformer winding 6,6 in inductive relation with the secondary winding 48;.

and through an anode load resistor 67 to an anode voltage source 68. The screen grid of the output amplifier tetrode 50 is coupled through a resistor 69 to the terminal of the anode load resistor 67 and the transformer winding 66, This Atermina-l of resistors 67, y69, and winding 66 is connected to one plate eachof parallel capacitors 70 and 71, the opposite plates of which are coupled to ground. The output of the output amplifier tetrode 50 is taken directly from the cathode thereof to termifinal 72this terminal being connected in parallel through a resistance` 73 and an inductance 74 to an output terminal 75 to a point of use.

The pulse amplifying triode 5 4 has its grid coupled through a grid resistor 8 0 to the cathode thereof, the cathode being coupled through a cathode resistor 81 to a negative voltage source Vat terminal 82. This grid is likewise coupled to oneplate of a capacitor 83, the opposite plate of which is coupled to the terminal junction inverted pulsel Br as shown-in FIGURE 2 `on -its anode output. Since the amplifier triode 15' is V'negatively biased and the V.input pulse first inl sequence of the waveform A is inverted in the secondary Winding 14 to produce a negative pulse on the grid of theV amplifier triode 15', this ktube will remain cut off and no signal Will be applied our, the output thereof. The `triode amplifier 15 will amplify the first in sequence `of the pulsesA in an inverted manner as shown by B by development of this signal yacross the anodeloadresistor 22 producing this pulse B across the primary. winding 20 of transformer 2:1.

j The windings 2t) and 30 of coupling transformer 21 are polarized,-as shown by the dots, which produce aninverted pulse on the ,secondary 30 providing a positive pulse on the grid of the blocking oscillator tube 31. Since the blockingr oscillator voutputl is taken from the cathode, the input signal Will be developed in an ampliiied for-rn across the cathode resistor 35 to produce lan am plified fast rising pulse kas shown by Dof FIGURE 2 onthe cathode output42.k This kfast rise time'is aided byvirtue of the. blocking oscillator connection of the triode 31 having it's anode coupled through a winding 37 in inductive relation with the secondary-winding 30 and y vpolarized reversely to the secondary Winding 3,0 ,to induce o f resistors 56 and 57. The cathode of pulse amplifier triode tube 54 is also kcoupled by a conductor 84 directly to thenanode. of the holding A.diode 53. The damping diode 52, `holding diode 53 and pulse amplifier 54l and their functions will `be more fully described in the descriptio-n of operation below.Y

The output from the lower driver circuit on the output g conductor .42' is capacitor coupled throughv the capacitor' to the control grid'ofa discharge triode 91. The grid l of the discharge triode 91 is biased through a grid biasing resistor 92 from a negative voltage source supplied at terminal 93. directly `coupled to a negative voltage source supplied at terminal 94, the negative voltage at terminal Y93 being greater than the negative voltage at vterminal l94. The anode of lthe discharge triode 91 is coupled by conductor means 95 directly to the cathode of the damping diode'- The cathode of discharge triode'V 911 is',

52, the common anode-cathode coupling being-.connected 1 directly to the control grid of the output amplifier tetrode 5t) through the conductor means 96. The discharge triode back the voltage drop across the winding 37 inversely as a positive wave inthe secondary winding 30 as readily understood by those skilled in the art of the'operation of blocking oscillators. The blocking oscillator operation thereby assists inthe devel-opment of an exceedingly fast rise timefor `the output pulse lD on the output conductor 42. y

The conductor 42, conducting the driver output pulse D, is coupled by the Vcoupling transformer 47 vthrough the secondary 48 and the anode winding V66 are polarized as shown by the dots to accomplish the aiding eect of the blocking oscillator circuit arrangement `.of the output amplifier tetrode 5l) to speed up Vvstill more the rise time or leading edge of the output wave F.` Prior tothe application of the driver pulse D the cathode of the tetrode 50 was biased to the'negative voltage from the negative voltage source 82 through the resistor 81, the conductor 84, and through the Zener diode 55 by exceeding the Zener voltage. The control grid of the tetrode 50 is biased below the cathode thereof by the coupling to the negative voltage source 82 through the pulse amplifier tube 54. Tube 54 is biased in a conductive state since grid voltage through resistor 80 is higher than the cathode voltage through resistor 81. Upon the application of the driver pulse D, the cathode voltage will follow or rise at which time this rise is reflected through the capacitor 59 to the anode of the holding diode 53 to cause conduction thereof or connection of the cathode of the tetrode 50 to the lead 51 of the secondary Winding 48 through the Zener diode 55 bringing this secondary Winding 48, and consequently, the control grid voltage of tube 50, up to near the cathode voltage, maintaining conduction of the tube. The gridto-cathode voltage' is broughtto zero by the grid leak resistor 58 which is the normal operating state for tube 50. This voltage is raised to the level permissibleby the voltage source 68 in circuit to the anode of tube 50 to bring the cathode voltage level to the plateau'level of the output square Wave F. This. voltage will be held at this plateau level by the hold diode 53 connecting the cathode of tube 50 to its control grid until a discharging voltage is applied to the control grid of the tetrode 50. It is to be noted that when the cathode voltage of tube 50 rises the cathode of the pulse amplifier Vtriode 54 will rise faster, by its direct connection through the conductor means 84 and capacitor 59 to'the cathode of tube 50, than the grid voltage of the vpulse amplifier 54, yby reason of the coupling through resistor 56 and capacitor 83, whereby pulse amplifier 54, accordingly, will be and remain cut off during the rise time and during the plateau time of the output pulse F.

Upon the application of the next in sequence or negative pulse A from the input transformer 12, this pulse will be inverted in the secondary Winding 14 to apply a positive pulse on the grid of the amplifier triode 15' to produce the negative pulse next in sequence on the anode output as shown by C in FIGURE 2. This negative pulse being applied as a negative'pulse through the secondary Winding 13 on the amplifier triode 15 will maintain this amplifier cut 0E or nonconductive. The pulse C on the anode of the triode amplifier 15' will be conducted through the transformer coupling of transformer 21 and beginverted in the secondary Winding 30 to produce a positive pulse on the grid of the blocking oscillator tube 31 to produce the fast rise, high peaked pulse E on the cathode output 42 of the blocking oscillator 31 in the same manner as described for the driver circuit 13 through 42. The polarity of the various windings in theV transformer coupling 21' are as shown by the dots. The driver pulse E will be applied through the capacitor 90 to the grid of the discharge triode 91 to overcome the negative bias on this tube and cause conduction to produce a fast decrease in voltage on the control grid ofthe tetrode tube 50 thereby tending to drop this grid voltage down toward the cathode voltage 94 of the discharge triode 91. The discharge triode 91 operates to short or rapidly drop the control grid voltage below the cathode voltage of output amplifier tube 50 to cause rapid cutoff. This immediately produces a drop in cathode voltage of the tetrode 50 which drop in voltage will be conducted through the capacitor. 59 to the cathode of the pulse amplifier .triode 54. This produces an immediate drop in voltage on the grid and anode of hold diode 53 and on the cathode of pulse amplifier 54 to cut off conduction of tube 53 and to make tube 54 conduct since the grid of tube 54 is held positive with respect to the cathode by the drop across resistor 56. Upon the conduction of the pulse amplifier triode 54, the secondary 48 by its lead 51 will be rapidly reduced in voltage toward the negative voltage source 82 which aids in reducing the control grid voltage on the tetrode 50 thereby producing a rapid fall time or trailing edge of the output pulse F. The pulse amplifier triode 54 thereby amplifies the voltage drop of the trailing edge of pulse F to reduce this voltage in the shortest possible time. By using the blocking oscillator circuits 31 and 31' in the driver circuits and by operating the tetrode 50 as a blocking oscillator, the rise time of the output voltage square Wave pulse F has been reduced from time in microseconds to a time range of 6 to 20 nanoseconds, and the trailing edge fall time by virtue of the pulse amplifier 54 has been decreased from time in microseconds :to a range of l5 to 30 nanoseconds. Thus, by decreasing the rise time and fall time periods, an output square wave F is produced that is nearer to a true square Wave than heretofore known to be accomplished. While various values may be applied to the several circuit elements and components, this circuit may be constructed and arranged to develop an output square Wave voltage of 500 volts rising from a negative 250 volts to a positive 250 volts then back to the negative 250 volts lto produce the 500 volts square Wave pulse.

While the invention is not limited in any Way to any values of the various elements or voltages, values Will be given herein merely for the purpose of example in carrying out an operative circuit arrangement but in no Way limiting to applicants invention. The following values may be used but maybe changed to meet certain circumstances or applications:

Capacitors: Values 18 and 18 .005 pf. (microfarads). 24 and 24 .01 pf. 25, 26, 34, and 40 50 auf. (micromicrofarads). 36 and 36 .001 prf. 41 and 41 .005 pf. 45 and 90 300 auf. 60 and 70 5 uf. 61 and 71 .02 pf. 59 and 83 .02 pf. Resistors:

16 and 16 10Ky (K: 1000). 22 and 22 2.2K. 23 and 23 2.2K. 32 and 32' 1K. 35 and 35' 470. 38 and 38 1K.

67 1K 69 60K l73 200.

82K. 81 and 92 47K.

Inductances: l

'74 8 microhenrie (uh). Voltages:

68 1000. 82 and 93 600. 94 500.

With these values the cathode of the output amplifier tetrode 50 will be held approximately at a -250 volts in the quiescent state of the circuit and will be driven to approximately +250 volts, as limited by the 1 kilovolt source 68 to establish the plateau of the -square wave output pulse F. Other values may be utilized for the capacitors, resistors, and inductance elements or the diodes 62 through 65 to establish different voltage levels for the output square Wave, where desired.

Many modifications and changes may be made in the constructional details and features of this invention to provide similar results, as by using the output amplifierr 5.0 as a straight amplifier and not as a blocking oscilla'- tor. Also, a triode could be used in place of the tetrode 1 50 as a blocking oscillator or as a straight amplifier withoutdeparting from this invention..l The departure from using a blocking oscillator fork the tetrode or `triode circuit would increase the rise time somewhat but wouldv operate successfully. While these and other modifications 'can be made without departing from the invention, it is to i be understood that we desire to be limited only by the spirit and scope of the appended claims.

We claim:

1. A generator of fast rise and fall time square wave a first means coupled to said `cathode output `respon-V sive to a rise in cathode output voltage to a raisedV level asa result of said first input signal to produce said .driver-amplifier output signal to connect the cathode yto the grid 4of said output amplifier to hold said cathode output voltage at said raised level; and

a :second means coupled to said output amplie'r tube circuit grid and to the output of said other driveramplifierycircuit in response to the second in sequence of said input signals to short said koutput amplifier whereby a square wave is produced on the cathode output with fast rise and fall leading and trailing edges with a fiat top sustained by said first means. e

2. A generator of fast rise and fall time square wave pulses comprising:

a pair Yof driver-amplifier circuits responsive to opvpositely poled first and second input signals to produce amplified first and second output signals respectively from` each driver-amplifier inthe sequence of the input oppositely poled signals;

an output amplifier tube circuit having a grid coupled to the output of one` of `said driver-amplifiers responding tothe first of said sequence of poled input signals to produce `a raisedwvoltage level on a cathode output thereof;

a first means coupled Yto said cathode output responsive to said raised voltage level as a result ofpsaid one driver-amplifier output first Ysignal to connect the .i

cathode to the grid of saidoutput amplifier to hold said cathode output voltage at saidraised level;

a second means coupled to said output amplifier tube n circuit-grid and tothe output of the other driver-amplifier circuit to receive said second output signal in response to the second in sequence of said input sig-k Y nals to remove said raised level voltageon the grid Y of said output amplifier and causepa voltage drop Y on said cathode output; and a, a pulse amplifier coupled across the grid and cathode output of said output amplifier and responsive to said voltage drop on said cathode output to drop said raised voltage level on said grid and to amplify the drive of said cathode output voltage down rapidly upon theapplication of said other driver-amplifier second output signal whereby square wave voltage..

pulses with fast rise and. fall leading and trailing edges said coupling of said output amplifier gridwithsaid Y Y which secondary has al damping diode thereacross to dampen out signal overshoots.

4. A generator of fast rise and fall time square wave pulses;

a pair of blocking oscillators;

a first transformer couplingV an input of vpositive and negative pulse signals to said pair of amplifiers in a Vpair of amplifiers responsive kto amplify positiveY opposite polarity relation to make-one amplier re-` sponsive to positive pulse signals from positive pulse Asignals applied to saidfirst transformer and the other amplifier responsive .to positive. pulsesignals from negative pulse signals applied to said first transformer; t second-and third transformers coupling one each ampli- 4fierwith one each blocking oscillator; l an output amplifier having a grid input and a cathode output;

a fourth transformer: coupling the output of said blocking oscillator coupledto-said one amplifieriwith the grid input of said output amplifier to produce a voltage raised level on saidcathodeoutput when a Y positive pulse signal is applied to said first trans- 7 former'input;

first meansY coupledV to said cathode output and said output amplifier grid responsiveto said voltage raised level onvsaid cathode outputto hold said grid` voltage ofsaid output ,amplifier at said raised level; andy a ksecondfrneans coupled `to said output amplifier grid and tothe output of said blocking` oscillator coupled tosaid Vother amplifier to discharge therraisedlevel voltage on the grid of said output amplifier upon the application lof a negative'pulse 1signal at-V said first transformer to cause said voltage level to fall on saidcathode outputV whereby a square wave is generated at saidgcathode output with fastrise and -fallleading and trailing edges corresponding in time to ,said positiveand negative pulse signals applied at said first Y transformer;n Y 5. A generator" of fast rise and fall time square wave pulses as set forth in claim 4 wherein y said first means'is a Zener diode and vacuum tube diodejcombin'ation.,coupledbetween saidcathode and grid of said output amplifier tube to cause the cathode raised voltage levely to hold the grid voltagev at the raised voltage level until said grid is discharged by said V"second means. 6. A generator of fast rise and falltirney square wave pulses-as set forthin claim S wherein said second means is a triodef .tube having. an anode coupled to, said output amplifierxgrid, a cathode cou-` pled to. a negative ,voltage source, and a grid coupled` to said Vblocking oscillator coupled to said other amplifier. 7. A Agenerator of fast rise and fall time square wave pulsesyasset forth in claim 6 wherein said; output1amplifier-tube is a tetrode, the screengrid thereof'being'coupled to a voltage supplypand to the j cathode thereof'through-a diode'means to limit the voltage level on said screen grid. 8.V A generator of fast riseV and fall time square Ywave pulses. as set forth in claim 7 wherein f said fourthtransformercouples the grid ofsaid output amplifier through'its'lsecondary, thesecondary of which is:dan`1ped in'overshoot oscillationsby a damping diode'across said `secondary. n 9.l A generator of fast rise and fall time square wave Y pulses as set forth in claim 8 wherein one (of `said 4driver-amplifiers is through a transformt er, the .Secondary of which couples said grid and said fourth transformer secondary'coupling to said output amplifier grid includes a triode pulse amplifying tube network with 'an anode thereof coupled to said secondary, `a grid coupled through a capacitor and a resistor in series to said cathode'output, anda cathode Vcapacitor coupledy to said cathode output produce a rapid fall time trailing edge of said generated square wave pulse.

lil

coupling transformer to dampen positive pulse overswings of said one blocking oscillator output;

a hold diode having an anode coupled to said cathode output and a cathode coupled to said coupling transformer secondary to hold the control grid voltage of said output amplifier at the raised voltage level of said cathode output subsequent to a positive pulse input applied to said control grid; and

10. A generator of fast rise and fall time square wave pulses comprising: a pulse triode amplifier having an anode coupled to an input transformer having a primary winding Vfor 10 said coupling transformer secondary, a grid coupled receiving positive and negative pulses in a predeterthrough a capacitor and a resistance in series to said mined time sequence in that order and having two cathode output, and a cathode coupled through a secondaries oppositely polarized; capacitor to said cathode output and through a rea pair of amplifiers, one each coupled to one each of sistance to a negative voltage source to rapidly resaid input transformer secondaries to cause one of duce cathode output voltage upon discharge of said said amplifiers to amplify a positive input pulse and raised voltage level on said output amplifier control to cause the other amplifier toamplify the negative grid and cutoff of said output amplifier whereby a input pulse, in that order of occurrence, on the refast rise time leading edge is generated by operation spective outputs thereof; of -said positive input pulse to a predetermined a pair of blocking oscillators, one coupled to said one 2() clamped amplitude Where it remains until discharge amplifier output andthe other coupled to said other by operation of said negative input pulse to produce amplifier output to produce a sharp rise, high amplitude positive pulse on said one blocking oscillator out- Output put corresponding to each positive input pulse, and a 11. A generator of fast rise and fall time square wave sharp rise, high amplitude positive pulse on said PulSeS eS Sel fOrtlln Claim 10 Whereln other blocking oscillator output corresponding t0 said hold diode has a Zener diode in its anode coupling said negative input pulse, said one amplifier and one to said cathode output, oriented with the anode thereblocking oscillator and said other amplifier and of coupled to the hold diode anode andthe cathode other blocking oscillator veach constituting a driver thereof Coupled l0 Said Output Cathode, t0 maintain n0 a bias on said output cathode and to pass a control circuit; o an output amplifier tube circuit having a control grid Voltage t0 Seid 'hold diede.

12. A generator of fast rise and fall time square Wave input, a screen grid and an anode coupled to an anode voltage source, and a cathode output to produce a PnlSeS 2S Set forth in Claim l1 wherein raised voltage level thereon when a positive voltage said output amplifier is coupled as a blocking oscillapulse is applied to said control grid, said screen grid '[01' umpllllef, Said Output anode being Coupled and cathode being coupled through diodes to provide through a transformer Winding t0 Said anode voltage a limited screen grid potential for said output am- Source, Suid transformer Winding being in nduCiVe plifier; relation to said coupling transformer secondary and a coupling transformer coupling the output of said one in OPPOSle Polarity tl1efet0- blocking oscillator to the control grid of said output 13- A generator 0f fast Ilse and fall tiIne Square Wave amplifier through a secondary Winding; pulses asset forth in claim 12 wherein a discharge triode having a grid coupled to the output Said One afnPlef and One blocking OSCllaOl' in One of said other blocking oscillator, an anode coupled to drivel: Channel and Said other amplifier und Other the control grid of said Output amplifier, and a cab blocking oscillator in the other driver channel are ode coupled to a negative voltage source to discharge each transformer coupled' control grid voltage on said output amplifier and cut off conduction; t

a damping diode coupled cross the secondary of said No references cited.

ARTHUR GAUSS, Primary Examiner.

a substantially optimal square wave on said cathode 

1. A GENERATOR OF FAST RISE AND FALL TIME SQUARE WAVE PULSES COMPRISING: A PAIR OF DRIVER-AMPLIFIER CIRUCITS RESPONSIVE TO OPPOSITELY POLED FIRST AND SECOND INPUT SIGNALS TO PRODUCE AMPLIFIER OUTPUT SIGNALS ON AN OUTPUT OF EACH IN THE SEQUENCE OF THE OPPOSITELY POLED SIGNALS; AN OUTPUT AMPLIFIER TUBE CIRCUIT HAVING A GRID COUPLED TO THE OUTPUT OF ONE OF SAID DRIVER-AMPLIFIERS RESPONDING TO THE FIRST OF SAID SEQUENCE OF POLED INPUT SIGNALS, AND HAVING A CATHODE OUTPUT; A FIRST MEANS COUPLED TO SAID CATHODE OUTPUT RESPONSIVE TO A RISE IN CATHODE OUTPUT VOLTAGE TO A RAISED LEVEL AS A RESULT OF SAID FIRST INPUT SIGNAL TO PRODUCE SAID DRIVER-AMPLIFIER OUTPUT SIGNAL TO CONNECT THE CATHODE OF THE GRID OF SAID OUTPUT AMPLIFIER TO HOLD SAID CATHODE OUTPUT VOLTAGE AT SAID RAISED LEVEL; AND A SECOND MEANS COUPLED TO SAID OUTPUT AMPLIFIER TUBE CIRCUIT GRID AND TO THE OUTPUT OF SAID OTHER DRIVERAMPLIFIER CIRCUIT IN RESPONSE TO THE SECOND IN SEQUENCY OF SAID INPUT SIGNALS TO SHORT SAID OUTPUT AMPLIFIER WHEREBY A SQUARE WAVE IS PRODUCED ON THE CATHODE OUTPUT WITH FAST RISE AND FALL LEADING AND TRAILING EDGES WITH A FLAT TOP SUSTAINED BY SAID FIRST MEANS. 